Six Cambodians have been held for questioning in connection with the disappearance of a 21-year-old British woman who went missing on an island popular with backpackers, as police on Tuesday said hopes were fading of finding her alive.

Nearly 200 army, navy and police personnel scoured Koh Rong island in southern Cambodia for a sixth day to find tourist Amelia Bambridge, who was last seen at a beach party on October 24.

A bag and phone were found where she was sighted on Police Beach, a late-night hangout popular with travellers, with British media reporting the alarm was raised after she failed to check out of her hostel.

Six Cambodians, some of whom work in the island's bars, have been taken to police headquarters of neighbouring coastal province Sihanoukville, a senior officer told AFP on Tuesday.

But another senior police source said there was ‘little hope’ that Bambridge will be found alive after a days-long hunt yielded few clues to her whereabouts.

‘We are looking for a body now,’ said the official, who is part of the search party, requesting anonymity.

Bambridge's distraught family -- who have been regularly posting on Facebook asking for information for their daughter's whereabouts -- are in Cambodia and have been shuttling between Sihanoukville and Koh Rong as the search intensifies.